This paper shows how to apply square root Kalman filtering to high speed data transmission on fading dispersive high-frequency (HF) channels. High data-rate HF transmission can be achieved by use of a single carrier bandwidth efficiency modulation that is demodulated with decision-feedback equalization (DFE). The DFE coefficients are updated adaptively by square root Kalman algorithms. Theoretical formulation and mechanization procedures for the square root Kalman algorithms are given. Computer simulation indicates that good error-rate performance can be achieved with these algorithms for rapid fading HF radio channels.

Narrowband jamming and interference due to other users in spread spectrum communication systems can be effectively suppressed by using digital whitening. As a result, an impressive improvement in receiver performance can be obtained. The digital whitening is accomplished using a transversal filter whose coefficients are selected by either a Wiener algorithm or a maximum entropy algorithm. Filters obtained by use of these algorithms are evaluated for various jamming and signaling conditions and are found to exhibit comparable performance over a wide range of input signal-to-noise ratios.